As an apparatus used for manufacturing a semiconductor device, there is an etching apparatus which etches various films on a substrate. For example, an RIE (Reactive Ion Etching) apparatus generates plasma of an etching gas by applying electromagnetic wave or the like to the etching gas in a reaction chamber and applies a radio frequency voltage between an upper electrode and a lower electrode, Accordingly, ions or radicals in the plasma are allowed to collide with the substrate, so that various films on the substrate are etched.
In such an RIE apparatus, a siloxane-based seal member (Q-PAD and the like) having a heat conductivity and an electric conductivity is used between a backing plate and a Si (silicon) electrode.
However, if siloxane is used for the seal member, the seal member has almost no plasma resistance, so that its lifecycle is short, and the seal member may cause a problem in electric contact points. Therefore, a seal member which has high plasma resistance and does not cause a problem in electric contact points is required.